Methods for removing a cataracteous and/or presbyopic natural lens from the capsular bag of the eye and replacing it by a lens-forming liquid material injected directly into the capsular bag are under development. Such methods have been described for example in Swedish patent application SE 0001934-9. The liquid material is a partially polymerized material, which can undergo a curing process in the eye and thereby form a solid lens implant. The lens implant acts as a substitute for the natural lens and aims to substantially restore the features of the natural lens of a young eye. Materials and methods suitable for injection and subsequent formation of an IOL (intraocular lens) are disclosed in WO00/22460, WO00/22459, WO99/47185 and in SE 0001934-9. A defect natural lens matrix can be removed by conventional surgical methods, e g involving an ultrasound probe, such as a phacoemulsification method involving aspiration. In order to facilitate the removal of the lens matrix and the refilling with lens-forming liquid material, a capsulotomy, typically a capsulorhexis, is prepared in the anterior wall of the capsular bag. The capsulorhexis is prepared from a circular or essentially circular capsulotomy in the capsular bag wall, typically with a diameter of from about 0.5 to about 2.5 mm. Subsequently, an injection syringe needle is inserted through an incision in the eye and through the capsulorhexis into the capsular bag, and the lens-forming liquid material injected into the capsular bag.
It has been identified as a problem in capsular bag filling processes that liquid material can leak through the capsulorhexis during the injection and before the final lens is formed. For this purpose, a plug is proposed in the Japanese patent specification JP97-308946. This plug is adapted to be attached to the injection syringe needle and inserted into the eye, and positioned in the right position in the rhexis when the syringe needle is inserted. Since the plug is relatively large and adapted to stay in the rhexis permanently, optical problems could arise. Furthermore, it needs a relatively large opening in the eye to be implanted. The plug also comprises a filling tube, which has to be cut off after filling. The tube could cause a leak. The size of the plug may also influence the free movement of the capsule that is needed for even deformation of the capsule during accommodation.
In WO00/49976, a more simple plug construction is suggested, which attempts to act as a valve during the surgical process. This plug, too, suffers from the drawback that parts of its structure are permanently located outside the capsular bag after finalization of the surgery. The curved flexible member is permanently protruding from the capsular bag through its hub-like attachment point to the flexible discoid flap-valve member. Consequently, the protruding parts may risk to compromise surrounding delicate eye tissues, including the iris, while they also risk generating unwanted optical side effects.
In a study of lens regeneration in rabbits and cats, A Gwon and co-workers used a collagen patch to seal a capsulotomy (J Cataract Refract Surg 19:735-745). Lens extraction was performed through an anterior capsulotomy, and the capsulotomy was sealed with a collagen patch. In some of the animals studied, the fibrin sealant Tissucol® (Immuno AG) was applied over the collagen patch subsequent to the application thereof. The injection of a lens-forming composition into the capsule in connection with the capsulotomy is not discussed, since the object of the conducted experiments was the study of spontaneous lens regeneration. Thus, the circumstances of these experiments differ in many respects from those of a surgical procedure contemplated in the context of the present invention. The differences include, among other things, that in the experiments of Gwon et al, a gas was injected into the capsule. Furthermore, the capsulotomy prepared was of a size significantly larger than that used in lens replacement surgery. Also, keeping a collagen patch in place in experiments with empty lens capsules, such as those described by Gwon et al, differs substantially from the situation encountered when a plug is applied to stop leakage of an injected lens-forming composition, inter alia because of the pressure exerted by such material on the capsulorhexis plug from inside the capsule.
Thus, there remain problems with known plug parts or sealing means for an opening in the capsular bag in the context of capsular filling processes. Accordingly, there is a need for improvements in such plug parts or sealing means.